A-LevelMathematicsProbability and statistics9709/61 · Oct/Nov 2017 · Q14 Marks
The discrete random variable X has the following probability distribution. x | 1 | 2 | 3 | 6 P(X = x) | 0.15 | p | 0.4 | q Given that E(X) = 3.05, find the values of p and q.
- The discrete random variable X has the following probability distribution. x | 1 | 2 | 3 | 6 P(X = x) | 0.15 | p | 0.4 | q Given that E(X) = 3.05, find the values of p and q.[4]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2017). The mark or mark type is shown in brackets.
- [1] p + q = 0.45 (Equation involving ΣP(x) = 1)
- [1] 0.15 + 2p + 1.2 + 6q = 3.05 (Equation using E(X) = 3.05)
- [1] Solving simultaneous equations to one variable
- [1] Both answers correct
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